In optical communication technology, large volumes of data are transmitted in complex networks, optoelectronic modules for a plurality of optical channels being used within a system. In particular, optoelectronic modules equipped with a transmission channel and a reception channel, so-called transceivers, are used for this purpose.
So-called small form factor (SFF) transceivers and small form factor pluggable (SFP) transceivers of small design are known. The transceivers may be of pluggable design (SFP transceivers) or be fixedly arranged in a housing on a main circuit board of an assembly of an optical communication system (SFF transceivers). The advantage of pluggable transceivers is that they can subsequently be inserted into a system and be exchanged simply and the system can thus be adapted simply to the respective stipulations of the optical network.
The known transceivers have, in addition to an optoelectronic transmission module and an optoelectronic reception module, an internal printed circuit board that runs parallel to the optical axis of the transceiver and contains electronic circuits for the converter module, such as a driver module and/or a preamplifier module. The transceiver is arranged altogether on a main circuit board of an assembly of the optical communication system, which is electrically connected to the internal printed circuit board via a plug, for example. An SFP transceiver is described in DE 101 14 143 A1, for example.
FIG. 10 shows an SFP transceiver 100 according to the prior art, in which two receptacles 201, 202 for a respective optical plug are provided, by means of which a respective optical waveguide can be connected to an optoelectronic transmitter or receiver. The transceiver 100 serves for transmitting optical signals of two data channels.
Furthermore, bidirectional modules are known in which a transmitter and a receiver are incorporated in a common housing, for example a customary TO housing with a window cap. The transmitted and received optical signals are separated from one another by means of a beam-splitting element in the common housing. A plug bay for coupling an optical plug may be adjusted and fixed directly to such a TO housing. Moreover, such a module is small enough to be incorporated in a transceiver module of SFF or SFP design. However, the optoelectronic performance of such bidirectional main circuit boards is not outstanding. Since the transmission group and the reception group are seated in a common housing, electrical crosstalk can be avoided only with difficulty. The restricted sensitivity and the limited optical power have the effect that such modules are preferably used for point-to-point applications.
WO 02/095470 A1 discloses an electro-optical module for the transmission and/or reception of optical signals of at least two optical data channels, in which at least two optical waveguide sections having in each case at least one beveled end area are provided. The optical waveguide sections are positioned axially one behind the other at the beveled end areas in a small optical tube. For a specific optical channel, light is coupled in and light is coupled out at the beveled end area of an optical waveguide section perpendicular to the plugging axis of the optical waveguide. In this case, the end area is coated with a wavelength-selective filter for wavelength separation purposes. What is disadvantageous about this arrangement is that use in a transceiver module of SFF or SFP design is difficult to realize. In particular, the small tube with the optical waveguide cannot be arranged centrally in the module for space reasons.
A plurality of assemblies of optical communication systems have been arranged in switchgear cabinets or rack cabinets and the respective SPF transceivers have been arranged on the respective main circuit boards of the assemblies in such a way that the transceivers can be plugged on from the end side of the respective switchgear cabinet or rack cabinet parallel to the main circuit board. Furthermore, a clip has been provided at the end side of the transceivers, which clip has enabled the respective transceiver to be removed or latched on the rack cabinet or on the main circuit board.
Since the available area of the end sides of the switchgear or rack cabinets is limited, optoelectronic modules, in particular transceiver modules for the SFP design, are sought which make use of the available area efficiently and enable a high number of optical channels to be coupled in or out per unit area. Furthermore, the intention is to ensure that the optoelectronic modules can be exchanged simply in conjunction with reliable operation.